This invention relates generally to plastic fluid handling equipment such as plastic diaphragm pumps and more particularly to grounding of this equipment to prevent static discharge.
This invention is applicable to the various components in a fluid handling system including but not limited to pumps, valves, accumulators, nozzles, regulators, piping, etc. In particular, the current line of plastic diaphragm pumps and components available in the marketplace cannot be effectively grounded. As material flows through the system, static electricity is generated and accumulates on the metal components (especially fasteners) of the plastic diaphragm pumps and accessories. Independent lab testing has shown that sufficient energy can accumulate which could result in a static discharge. If the environment in which the pump is operating contains a flammable mixture of gases or dust, the discharge could ignite the atmosphere causing an explosion. Since the thermoplastic materials commonly used in plastic diaphragm pumps and . components are nonconducting, the metal components cannot be grounded effectively without physically wiring them together. The wiring is time-consuming and the completed wiring subject to physical damage and corrosion which may negate the effective ground.
In one approach to this problem, plastic pumps have been developed and are on the market which are conductive, however, they have several limitations. In general, these pumps use heavy loadings of carbon black to obtain the desired conductivity. This has an adverse effect on the mechanical properties of the plastic and the carbon can leach into the fluid being pumped thereby contaminating the fluid.
In addition, the pumps in general are molded in polypropylene which is not compatible with materials such as, but not limited to, MEK, XYLENE, TOULENE, ACETONE, solvent based paints and stains. Polypropylene softens, swells and mechanical strength is lost when exposed to the above fluids.
The foregoing illustrates limitations known to exist in present conductive plastic pumps and pump systems. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.